How to reach Tower of Frozen Shadow
The Tower of Frozen Shadow is located on the larger middle island in Iceclad Ocean. The two easiest ways to reach this location is by getting a Wizard to port you to Iceclad Ocean or to take the boat from North Ro to Iceclad Ocean then hoof it here.
Alternatively if you have access to the Guild Hall (meaning DoN is live on your server) then you'll be able to reach Iceclad via Guild Hall portal. Once you're in Iceclad you'll want to follow my blue lines on the map above to reach the doorway shown in the screen shot below. Clicking on this doorway will grant you access to the Tower of Frozen Shadow.